Walkman is actually a Sony trademark and was the name used for portable tape or cassette deck players. These were meant for the listening pleasure of a single person and the trademark was later expanded for other portable Sony devices for audio and video entertainment. The term Walkman is also given to a range of the Sony Erricson range of mobile phones which also became immensely popular. Walkman was a device that was designed and created by audio engineer Nobutoshi Kihara who worked for Sony.
The Sony co-chairman Akio Morita wanted a device where he could listen to his favorite operas during the Trans Atlantic flights. The concept was well liked and was originally marketed in Japan in 1979 and was sensational, since it gave freedom to young people to listen to their music with light weight headphones.
Even though Morita hated the name Walkman, the name stuck on and the promotional campaign using the name had already begun and to change the name midway would have been extremely expensive for the company. In 2007 March, the digital flash based video walkman was released and was named the A800 series.
The Walkman by Sony faced stiff competition from other companies such as Toshiba, Aiwa, Panasonic etc, but the personalization of the gadget worked in its favor for almost 20 years and the essential design remained unchanged.